Prevalence Rates of Multiple Sclerosis
Vitamin D Status
Sun Exposure: Mean UV Index
MS Rates and Vitamin D
MS Rates and Sun Exposure
Sun Exposure and Vitamin D
per 100,000

No Data

MS prevalence data is shown in a rate of MS per 100,000 people. The data was collected by the Multiple Sclerosis International Federation and published in 2007 as the Atlas of MS Database

Choose a country, and then select two sets of data to compare.

Prevalence Rates of Multiple Sclerosis
Vitamin D Status
Sun Exposure: Mean UV Index

Prevalence Rates of Multiple Sclerosis
Vitamin D Status
Sun Exposure: Mean UV Index

Understanding the Connection Between Vitamin D and MS

Multiple sclerosis (MS) is one of medical science's biggest mysteries. It's entirely unclear what causes this chronic autoimmune disease.

For years, many researchers have been pointing out a possible connection between the prevalence of multiple sclerosis and sunlight exposure—specifically, in terms of the role ultraviolet radiation in our bodies' vitamin D production. And, while the link between vitamin D and MS remains fuzzy at best, new findings have further spiked interest in the subject.

Recent studies show what appears to be a negative correlation between exposure to UV radiation and MS. In other words, the lower the exposure to radiation from the sun, the higher the risk of MS.

Due to the Earth's shape and its rotation around the sun, the intensity with which sun radiation hits different regions of the planet will depend on their latitudes—the closer to the equator, the higher the intensity. The underlying idea is that less radiation hinges the body's natural production of vitamin D and, thus, could lead to a higher risk of developing MS.

The purpose of this tool is to allow us to visualize this possible relation between sun radiation—measured by the ultraviolet index—, vitamin D rates, and MS prevalence throughout the world.

So, is there a connection?             

What Our Data Tool Found

By comparing countries with similar standards-of-living, but at different latitudes, you can quickly begin to see how sun exposure and vitamin D rates might affect how common MS is.

For example, Canada has one of the world's highest rates of MS and, due to the country's distance from the equator, its residents get considerably lower levels of UV radiation. 

In comparison, the United States has an average UV index twice as high as its neighbor's and MS rates almost half as low. 

Even within the same country, MS prevalence rates seem to increase in areas further from the equator. A recent study published in the Journal of Allergy and Clinical Immunology showed that North of Scotland has the highest rates of MS in the United Kingdom (Milliken, et al., 2012). Similarly, another study by the University of Tasmania in Australia, concluded that Tasmanians were "seven times more likely to have MS than people in Northern Queensland and the Northern Territory" (Stewart, et al., 2012).

The same case could be made for neighboring countries such as France and Germany where, while sharing a similar geography, their small difference in latitude—Germany is about five degrees farther north—makes for a big difference in terms of the variables we're looking into:

 

Unfortunately, the relationship between sun radiation exposure and vitamin D rates doesn't always come across so clear.

For example, take the country Spain. Spain sits at similar latitude to the U.S., and, as a result experiences similar UV indexes. Nonetheless, the U.S.'s vitamin D rate almost doubles that of Spain.

Why is that? It's hard to say. While sunlight is the main source of vitamin D, eating habits and the use of of vitamin D supplements can also play a role. While no major studies have been done comparing the average Spanish diet to an American diet, it may be the case that Americans tend to get more dietary vitamin D. For example, pay attention to your orange juice tomorrow at breakfast—you may not have noticed before, but many brands of orange juice "infuse" their product with vitamin D.

The Bottom Line

What is fairly clear is that MS is more prevalent in certain geographical areas, and these all tend to be further from the equator. High latitudes and, therefore less exposure to intense sunlight means a higher risk for MS.

What is less clear is why.

The connection between vitamin D, sun exposure, and MS remains unclear. The good news is that some of our best scientists are on it. For example, Australian researchers are about to launch the world's first large-scale clinical trial to measure vitamin D's effectiveness as a preventative treatment for MS.

More Information

In the meanwhile, here are some additional resources to learn more about MS: